Leadership and clinical decision-making skills are critical in the practice of safe medicine, particularly for providers in fields where seconds can mean the difference between life and death. Cultural norms, beliefs and assumptions that each person holds can influence leadership performance as well as individual team members' interpretations of leaders' actions and behaviors in response to others. Aims: This grant aims to: I) Characterize residents' perceptions of leadership and the clinical situations and mechanisms by which gender affects leadership and teamwork through a national survey of Emergency Medicine (EM) and Obstetrics & Gynecology (Ob/Gyn) resident physicians; II) Engage national leaders in simulation, leadership, teamwork, and medical training to develop simulation-based expert model leadership training that leverages strengths and compensates for challenges faced by male and female leaders to improve effective leadership and promote patient safety; and III) Conduct a large multi-centered randomized controlled (RCT) trial to evaluate the effectiveness of tailored leadership training on self-perceived and objective leadership skills and team performance. Methods: We propose to conduct a national survey of all EM and Ob/Gyn residents at academic medical centers to understand how gender affects leadership and teamwork (Aim I), develop a simulation-based, gender-sensitive training with the help of national leadership, teamwork, and clinical experts (Aim II), and conduct a RCT of that training with EM and Ob/Gyn resident physicians at selected sites across the country, evaluating the effectiveness of the training through simulation (Aim III). Significance: Leadership is an important element of effective teamwork. In the hospital setting, effective leadership and teamwork leads to greater patient safety. Using simulation to create tailored leadership training that takes into account societal biases about gender and leadership will create better leaders and ultimately create a safer patient healthcare experience.